Antennas for radar sensors, which are provided for use in motor vehicles, are frequently designed as patch antennas on an HF substrate. This permits a cost-effective construction of the radar sensor. When array antennas are used, the desired directional characteristic of the radar sensor is able to be achieved in azimuth and/or in elevation, without requiring a radar lens. Separate antennas are frequently used for the radiation of the radar signal and for receiving the reflected signal. The desired directional characteristic of the transmitting antenna in azimuth is achievable by supplying the microwave power to the plurality of antenna elements juxtaposed on the substrate in the same phase. A radar lobe is then created by interference, whose main radiation direction is oriented at a right angle to the plane of the substrate, and which covers an azimuth angle range of about −45° to about +45°. On the receiving side also a plurality of juxtaposed antenna elements or patches are used, which belong, however, to different receiving channels, so that, based on the phase differences between the signals received by the different antenna elements, one is able to draw a conclusion on the azimuth angle of the object.